This invention relates to a structure interlinking the axle with the hubs of steering drive wheels, particularly for use on agricultural tractors, which comprises two cup-shaped bodies, being respectively unitary with the axle and the hub and face coupled together in a relationship of relative rotation about the steering axis of the wheel, said cup-shaped bodies defining, on the interior thereof, a sealed cavity wherethrough the drive means to the hub is passed.
In accordance with the prior art described in Italian Patent Application No. 41600-A/89 by this same Applicant, the face coupling of the two cup-shaped bodies is provided by two bracket-like retaining formations being connected, the one to the axle by screw fasteners, and the other to the body of the wheel hub, also by screw fasteners.
Between the brackets and the respective, oppositely located cup-shaped bodies, according to the prior art of the above-noted document, there are placed thrust and rotation elements, usually plain bearing assemblies adapted to create rotary spindles whose axes coincide with the steering axis of the wheel.
The structure of the above-noted prior art, while being satisfactory under the aspect of providing a virtually sealed cavity between the cup-shaped bodies which can enclose an equal-velocity joint for transferring the motion to the wheel hub, still has the drawback that it allows mud and dirt to enter the interspaces that form of necessity between the mounting brackets for the cup-shaped bodies, with consequent likelihood of the bearing members becoming jammed which define the wheel steering axis between said brackets and their respective cup-shaped bodies.
A further drawback that appears in a structure according to the aforementioned prior art originates from a considerable concentration of loads on the rotary drive connection members between the brackets and the cup-shaped bodies, which are subjected, therefore, to considerable wear and potential failure. Nonetheless, assembling such a structure is a relatively complex, and hence expensive, operation.